Optical fiber connectors are an essential part of practically all optical fiber communication systems. For instance, such connectors are used to join segments of fiber into longer lengths, to connect fiber to active devices such as radiation sources, detectors and repeaters, and to connect fiber to passive devices such as switches and attenuators. The principal function of an optical fiber connector is to optically couple a fiber with the mating device (e.g., another fiber, an active device or a passive device). This is achieved by holding the end of the fiber such that the core of the fiber is axially aligned with the optical pathway of the mating device.
To facilitate an effective optical coupling, the end face of the ferrule is typically polished. This is usually performed in a controlled setting wherein precision equipment and skilled personnel are available to cleave the fiber, terminate it in a ferrule, and polish the ferrule to exacting tolerances. Frequently, however, connectors must be terminated in the field where such facilities and personnel are not available. Under these conditions, it is desirable to omit the step of the polishing the ferrule by instead terminating the fiber in a connector which has a fiber stub already terminated and polished in a ferrule. The terminating fiber is optically coupled to the fiber stub in the connector, often with the use of a refractive index matched gel to improve optical coupling therebetween.
The terminating fiber is held in intimate contact with the fiber stub by virtue of a clamping mechanism, which applies a radial force to the terminating fiber to secure it to the connector. Advantageously, this clamping mechanism facilitates straightforward field assembly by obviating the need to handle epoxy and for curing ovens during field termination.
Tyco Electronics (Harrisburg, Pa.) offers a family of field-installable connectors that are axially-actuated (see, for example, U.S. Ser. application No. 20070127873, which is hereby incorporated by reference). Each connector comprises a connector housing, a ferrule assembly having a ferrule which projects from the front of the connector housing, a fiber stub which is contained in the ferrule and extends from the back of the ferrule assembly, a clamping mechanism behind the ferrule assembly into which the back end of the fiber stub extends, and a spring in the connector housing to bias the combination of the ferrule assembly and the clamping mechanism forward relative to the connector housing. The clamping mechanism comprises camming means and a plunger to actuate the camming means. These field-installable connectors are available as SC, LC and ST type connectors.
Termination of a fiber in a field-installable connector is typically performed using a tool resembling a pair of pliers. Specifically, the pliers comprise two arms that urge together when the tool is actuated or squeezed. One arm comprises a die, which is configured to receive the ferrule of the connector, while the other arm comprises a die that is configured to receive the plunger. After the fiber is inserted in the back of the connector and into the clamping mechanism, the unactuated connector is disposed in the pliers and they are squeezed causing the two arms to draw together, thereby urging the ferrule assembly back into the plunger. Because the clamping mechanism is sandwiched between these two components, the cam means are actuated by the plunger, and the fiber is secured to the clamping mechanism. Once released, the ferrule assembly returns to its forwardly-biased position within the housing.
Although field termination using the system described above is convenient, Applicants have nevertheless identified a number of shortcomings. For example, typically, there is a protective dust cover or cap on the ferrule that must be removed prior to actuation. Removing the protective cap prior to actuation, however, is undesirable for a number of reasons. First, it presents an opportunity for the ferrule to be damaged or otherwise compromised by the crimping tool. Likewise, during this procedure, debris may be deposited on the end face of the ferrule thereby diminishing its optical performance. Furthermore, removing the cap necessarily requires putting it back, thus, creating additional steps and the chance that the installer may simply forget to do so, thereby leaving the ferrule unprotected after fiber termination.
Therefore, what is needed is an approach for terminating a field-installable connector that does not subject the ferrule to damage and or debris by removing the cap. The present invention fulfills this need among others.